1. Field of the Invention
The present invention relates generally to disk drives, and in particular to a method of assembly of a disk drive including applying a holding force against a first VCM plate during engagement with a second VCM plate.
2. Description of the Prior Art
The typical hard disk drive includes a head disk assembly (HDA) and a printed circuit board assembly (PCBA) attached to a disk drive base of the HDA. The head disk assembly includes at least one magnetic disk, a spindle motor for rotating the disk, and a head stack assembly (HSA). The spindle motor includes a spindle motor hub that is rotatably attached to the disk drive base.
The head stack assembly has an actuator assembly having at least one transducer head, typically several, for reading and writing data from and to the disk. The printed circuit board assembly includes a servo control system in the form of a disk controller for generating servo control signals. The head stack assembly is controllably positioned in response to the generated servo control signals from the disk controller. In so doing, the attached heads are moved relative to data tracks disposed upon the disk.
In further detail, the head stack assembly includes an actuator assembly, at least one head gimbal assembly, and a flex circuit cable assembly. A conventional “rotary” or “swing-type” actuator assembly typically includes an actuator having an actuator body. The actuator body is configured to rotate on a pivot assembly between limited positions about an axis of rotation. A coil support extends from one side of the actuator body, and a coil is supported by the coil support. The coil is configured to interact with one or more permanent magnets to form a voice coil motor (VCM). Typically a pair of magnets is utilized, with a magnet being disposed on each side of the coil. The magnets each include a VCM plate, which is used to securely position the magnets. Energizing the coil results in forces that tend to pivot the actuator. A change in the direction of current through the coil results a change in the resulting pivot direction.
One or more actuator arms extend from an opposite side of the actuator body. To facilitate rotational movement of the actuator, the actuator assembly further includes the actuator body that has a bore and a pivot bearing cartridge engaged within the bore. Each magnetic disk includes opposing disk surfaces. Data may be recorded on a single surface or both surfaces along data annular regions. As such, the head stack assembly may be pivoted such that each transducer head is disposed adjacent the various data annular regions from adjacent an outer diameter (OD) to an inner diameter (ID) of each disk.
A topic of concern is the assembly/disassembly process in regards to the pair of magnets and the VCM plates and the actuator. One prior art assembly method includes attaching a first one of the magnets and its associated VCM plate to the disk drive base. This may be accomplished with one or more fasteners such as screws. Subsequently, the actuator may be positioned over the attached magnet and VCM plate. The second magnet and VCM plate may be then positioned over the actuator and the coil. An attractive force between the two magnets facilitates attachment of the second magnet and its VCM plate. The use of fasteners to attach the first magnet and VCM plate presents several problems. It is contemplated that the magnets and their VCM plates and the actuator may have to be disassembled during the life of the disk drive (such as for testing, maintenance or repair). Removal of the fasteners may result in the undesirable release of metal particles resulting in contamination within the disk drive. Further, the use of the fasteners require the additional step of their removal during the disassembly of the disk drive. An additional problem is that upon the installation of the second magnet and VCM plate, just before the moment of contact of the two VCM plates the attractive force of the two magnets result in a sudden engagement of the VCM plates. This may result in an undesirable release of debris due to damage of the impacting surfaces.
Another method of assembly of the disk drive, includes attaching the first magnet and its VCM plate to the disk drive base through adhesive bonding. This attachment, however, precludes the ready removal of the VCM plate during disassembly of the disk drive. Further, use of adhesives present contamination problems within the disk drive. As mentioned above, an additional problem arises due to the attractive force of the two magnets that results in a sudden engagement of the two VCM plates, which may result in an undesirable release of debris.
Yet another method of the assembly of the disk drive is to first assemble the two magnets and their VCM plates about the actuator. The magnets, the VCM plates and the actuator are then collectively installed into the disk drive base. Such a method, however, presents significant difficulties in the handling of such components during their collective installation because the magnets/VCM plates are not directly attached to the actuator.
As such, there is a need in the art for an improved method of assembly of the magnets and their VCM plates into a disk drive in comparison to the prior art.